The phrase "carbon backbone" refers to the chain or structure made up of carbon atoms in a molecule. It is like the skeleton or framework that holds the molecule together. Full definition
Or, with energy needs in mind, further processing could stitch the six -, seven -, and eight - carbon backbones of the obtained molecules into the chains of up to 14 needed to qualify as «drop - in» biofuels for jet fuel. (sciencedaily.com)
In 2014, the same group announced the first detection of an interstellar molecule with a branching carbon backbone. (newscientist.com)
Perfluorinated Chemicals, or PFCs are a family of chemicals where all molecules have carbon backbones fully surrounded by fluorine atoms. (wellnessmama.com)